1. Field of the Invention
The present invention relates to a method and a control unit for operating an internal combustion engine having exhaust gas recirculation, in which the air is supplied, via an intake manifold at least partially closable with the aid of a final control element, to at least one combustion chamber and a part of the exhaust gases flowing in an exhaust pipe is conducted via an EGR channel, which is at least partially closable with the aid of an EGR valve unit, into an area of the intake manifold which lies between the final control element and the combustion chamber.
2. Description of Related Art
A method for determining the air mass flow in internal combustion engines is known from published German patent document DE 10 2005 004 319, which ascertains the air mass flow in an intake manifold in that it not only detects a measured variable of an air mass sensor, but rather also ascertains the air mass flow using state variables, in particular a pressure before an engine intake, an air temperature before the engine intake, and an engine speed using the so-called “pTn method” (using thermodynamic state variables. In this method, the value detected with the aid of the air mass sensor is weighted less and less in relation to the value ascertained from the state variables with increasing operating time. The method for determining the air mass flow in the intake manifold is thus adapted to the aging and imprecision of the air mass sensor accompanying the increasing operating time of the internal combustion engine.